1. Field of the Invention
The present invention relates to a driving method and a driving device of an inkjet head that ejects one or more ink droplets to print a dot of a tone corresponding to the number of the ink droplets.
2. Description of the Related Art
An inkjet recording apparatus of a multi-drop type is conventionally known. The inkjet recording apparatus includes an inkjet head that successively ejects one or more ink droplets for printing a dot, and a drive voltage generator that drives an inkjet head. The inkjet head has a nozzle plate on which a plurality of nozzles are arranged in one direction, a plurality of pressure chambers that are communicated with the nozzles respectively at a front end, adjacent to each other, and separated by partitions, a common ink chamber that is communicated with a rear end of the pressure chambers to supply ink, and a plurality of actuators that change volumes of the pressure chambers in accordance with a waveform of a drive pulse signal supplied from the drive voltage generator as a drive voltage in a print cycle. Each of the actuators provides a pressure fluctuation to ink in the pressure chambers via deformation of a diaphragm. In this manner, the ink is ejected as one or more of ink droplets from a corresponding nozzle, and a dot of a tone corresponding to the number of the ink droplets is printed on paper.
In the inkjet recording apparatus described above, after a dot is printed by continuous ejection of ink droplets, an auxiliary voltage pulse is added to the drive pulse signal so that ink droplets are not unnecessarily ejected from the nozzles (for example, refer to Jpn. Pat. Appln. Publication No. 2004-1479).
In addition, in order to prevent excess ink droplets called satellites from being ejected from the nozzles, in a case where dot information for a next print cycle is non-ejection, the drive pulse signal is output with a time delay of a predetermined period from a start timing of the print cycle (for example, refer to Jpn. Pat. Appln. Publication No. 2002-234198).
However, according to principles of these documents, there has been a problem that control becomes complicated. In addition, there has been a problem that print speed is lowered when the drive pulse signal is output with a time delay of a predetermined period from a start timing of an original print cycle as described in Jpn. Pat. Appln. Publication No. 2002-234198.